The Sun is the center
of the solar system, accounting for almost the entire mass of the system.
Astronomers have studied the Sun for many years, but the advent of space
flight allowed telescopes and cameras to be taken above the obscuring
effects of the Earth's atmosphere. This photograph was taken from the
Skylab space station during August 1973. The Sun is seen through
a filter that only transmits light at extreme ultraviolet
wavelengths (less than the shortest wavelengths of visible light), in
this case, the wavelength of light emitted by ionized helium (304 angstroms).
This wavelength region is unavailable for study from the surface of the
Earth due to the absorbing effects of the atmosphere. Bright and dark
regions represent disturbances on the surface of the Sun possibly related
to the violent convection motion taking place in the outer layers of the
Sun. A very large solar prominence,
an eruption of solar material above the visible surface of the Sun, is
present on the left in this photograph. The scale of this activity becomes
evident when one considers that the diameter of the Sun is equal to more
than one hundred Earths lined up end to end.

Skylab photography
taken on August 21, 1973, by the Naval Research Laboratory ultraviolet
spectroheliograph (S79-36674).